1. Field of the Invention
The present invention generally relates to the propulsion and cooling systems for a personal watercraft. More particularly, the present invention relates to a propulsion unit assembly for a personal watercraft.
2. Description of the Related Art
Personal watercraft have become very popular in recent years. This type of watercraft is sporting in nature; it turns swiftly, is easily maneuverable, and accelerates quickly. Personal watercraft today commonly carry one rider and one, two or three passengers.
Personal watercraft typically incorporate an engine and associated components within a substantially sealed hull, with one or more air ducts piercing the hull to provide atmospheric air for cooling of the engine and for combustion. While atmospheric air may be sufficient for cooling smaller engines and associated components, as the engines incorporated into personal watercraft become increasingly powerful, cooling requirements for such engines and their associated components significantly increase. To accommodate these increased cooling requirements, therefore, various auxiliary cooling arrangements utilizing fluid from the jet pump unit have been proposed, including cooling of the oil and/or fuel used in the engine, as well as direct cooling of the engine itself. For example, some watercraft auxiliary cooling systems utilize ambient water pumped directly from the pressurization chamber of the installed jet pump unit through a conduit to the engine and/or associated cooled components. Typically attached to a fitting formed on the outer surface of the pressurization chamber, the cooling water conduit passes through the pump chamber, is routed through an opening in the tunnel wall, and travels through the hull interior to the a desired location.
In addition, as labor and production costs for manufacturing personal watercraft increase, manufacturers and consumers alike have become increasingly sensitive to the costs associated with the manufacture of personal watercraft. One time-consuming assembly step, and thus a significant expense in the manufacture of personal watercraft, relates to the installation of the propulsion unit onto the hull of the watercraft. Because the propulsion unit commonly must be adjusted with respect to the longitudinal axis of the watercraft for a proper coupling between the propulsion unit and the engine, propulsion units are often improperly aligned when initially installed on the watercraft hull and must be repositioned during the assembly process. When an alignment discrepancy is found, such units must be re-aligned and re-connected, normally by manufacturing personnel. Moreover, if the propulsion unit was sufficiently misaligned when it was originally installed, the numerous holes cut into the watercraft hull may be inadequate to effect proper mounting of the propulsion unit when in the proper orientation. In such a case, the watercraft hull might require significant repair and/or replacement before the propulsion unit may be properly re-installed.